I think changing colors randomly when it just feels right is stupid. Either you have to consistently change colors to match with user ranking ratios or you never change them, and I'm pretty sure most people don't want them to constantly change.

Perhaps I'm in the minority in thinking this, though I do not think I am, but for me I want to set goals and have comparisons that are always calculated in the same way, whether that's through ratios or static barriers or something else similar. If the bounds change arbitrarily at random whenever it just feels like it should, you have no ability accurately reflect on what the colors mean. However through consistency, people get a reasonable feeling of what each color means so they seem like good goals and comparisons.

We don't say it's going to be changed every month, but the latest time it's been (except some cosmetic changes) was $$$5$$$ years ago. I think one time per $$$5$$$ years would be rare enough to avoid this :)

Also, I can say that the recent time I am checking my progress not using rating as a metric, but only a place at the top list, because probably inflation has become very fast now(but it's only a subjective view and should be investigated).

I will agree that if it is changed consistently on some founded basis, then that would fit exactly the kind of idea I would like. For example if the colors were reformatted once a year based on amount of people that should be in each color, not arbitrarily, that would be a great way to keep the colors having the same meaning overtime and help reduce rating inflation.

I think there is some sort of balance point in the middle. Both extremes are less than perfect. On the one hand, being top 100 in the world right now is likely harder than it was 10 years ago, because there are more people doing it more seriously and over longer time span. On the other hand, being in top 1% in the world is likely easier now, because "I've been told that I need to do this to get a job" / "I will try this out of curiosity now when there are so many cool sites with cool competitions" kind of growth is likely even faster than the growth in number of people who take it seriously.

I remember there was a lot of concern that ratings were getting deflated not that long ago. Someone discovered in a contest the total number of rating points gained by all contestants was less than the total number of rating points lost.